The problem that the invention intends to solve is to develop a composition that, when it is extruded or coextruded, gives a surface with a rough feel, matt appearance and that is scratch and UV resistant. The composition must be easily processable under normal processing conditions, that is to say that it must be easily extrudable or coextrudable onto a thermoplastic polymer. The extruded or coextruded part must also have an adequate mechanical strength. The rough feel and the matt appearance may be characterized/quantified respectively by the roughness and the gloss of the surface of the extruded or coextruded part. Under well-defined processing conditions, the composition of the invention makes it possible to obtain a rough feel characterized by a roughness Ra>8 μm and a matt appearance quantified by a gloss <10%, indeed <4% (at an angle of 60°).
International application WO 01/12719 describes a methacrylic composition comprising from 0.5 to 50% of particles whose average size is greater than 100 μm, comprising MMA and optionally a comonomer, these particles possibly being crosslinked. The composition may be coextruded according to the capstock process onto a thermoplastic polymer such as PVC.
International application WO 97/14749 describes a methacrylic composition comprising crosslinked particles, whose average size ranges from 250 to 600 μm, dispersed in a PMMA obtained by the cast process.
U.S. Pat. No. 3,345,434 describes a composition having a rough feel obtained by blending an uncrosslinked thermoplastic polymer with particles of a crosslinked thermoplastic polymer. It could be for example a PMMA in which particles of crosslinked PMMA are dispersed.
U.S. Pat. No. 4,876,311 describes a dispersion of crosslinked particles in a thermoplastic polymer whose average diameter may vary between 5 and 50 μm.
European application EP 1 022 115 describes a methacrylic composition having a frosted appearance and surface roughness comprising highly crosslinked particles consisting of styrene and an alkyl (meth)acrylate having an average diameter ranging from 15 to 70 μm and a size distribution ranging from 10 to 110 μm.